Safety system for explosive powder storage bin

ABSTRACT

Prevention of deflagration of explosive powder from developing into a detonation within a storage chamber is accomplished by venting pressure from within the storage chamber so that the critical mass detonation rate of burning of the powder can never be reached.

i v o q 51 "i 1. i 4 5 iliie wees l me 1 1 Andrew 1 any 1, R973 [54] SAFETY SYSTEM FQR EXPLOSIVE 3,354,77l l 1/1967 Stark ..86/20 C POWDER STORAGE BIN 3,401,632 9/1968 Griffith et a]. 102/24 R [75] Inventor: Eugene A. Andrew, F lorissant, M0.

[73] Assignee: Oiin Corporation, New Haven, Primary Examiner-Vern" Pendegrass Conn Att0rneyDonald R. Motsko et al.

[22] Filed: June 25, 1971 [21] Appl. No.: 156,858 [57] ABSTRACT Prevention of deflagration of explosive powder from [52] U.S. Cl. ..86/1, 86/20 R developing into a detonation within a storage chamber 51 im. Cl. ..F42b 33/00, F42b 37/00 is accomplished y venting pressure from within the [58] Field of Search ..86/1, 20, 20 C; storage chamber 50 that the critical mass detonation 02/24 R 97 60/252 253 rate of burning of the powder can never be reached.

5 Claims, 3 Drawing Figures [56] References Cited UNITED STATES PATENTS 2,958,184 l 1/1960 Sanders ..60/223 Patented May 1, 1973 FIG sues/v5 A ANDREW INVENTOR ATTORNEY SAFETY SYSTEM FOR EXPLOSIVE POWDER STORAGE BIN This invention concerns the prevention of detonation of a charge of explosive powder within a storage container which would otherwise result from deflagration of the powder within the storage container.

In the manufacture of explosive or incendiary devices such as certain types of ammunition, large quantities of explosive material, such as smokeless powder and the like, must be stored. Such storage occurs in large containers, hoppers, or bins which can take the form of containers on assembly lines from which the explosive material is metered into the explosive devices being produced. Large quantities of explosive powder are also stored in other types of containers during various stages of production.

Storage of large volumes of detonatable explosive material, such as smokeless powder, and the like, is, of course, dangerous since ignition of the stored volumes of such material can result in detonation thereof with catastrophic results. This danger requires utmost precautions being taken in the storage areas, such precautions including the abolition of smoking, matches, lighters, and other devices which could cause ignition of the stored powder charges.

Notwithstanding such safety precautions, accidental explosions may still occur as a result of sparks caused by metal parts being dropped, defective electrical wiring, heat generated by friction in working mechanisms, and other causes which the most stringent safety precautions can minimize, but not eliminate.

This invention concerns the prevention of detonation of a stored volume of explosive material even if deflagration within the stored volume occurs. It is known that detonation of a confined mass of explosive powder will occur once heat and gas pressure (caused by combustion gases produced by the burning powder) become sufficiently high to cause the burning rate of the powder to reach a mass detonation rate, at which time all of the powder is substantially instantaneously consumed, causing an explosion. If the stored powder burns at a rate which is less than the mass detonation rate, no explosion will occur, and the powder will merely burn itself up. The mass detonation rate of a particular powder varies with the composition and physical shape of the powder, certain powders being fast burning, and other powders being slow burning. This invention provides for the venting of the burning area of the powder mass so that, if combustion of the stored powder mass occurs, the burning area is vented to the atmosphere so as to reduce combustion gas pressure before the mass detonation rate of combustion is reached. Thus the burning powder will merely burn itself up without detonating.

The venting can be accomplished by providing the storage container with blow out panels which will be dislodged by a combustion gas pressure which is below the pressure which will cause reaching of the mass detonation rate of combustion. Dislodging of the panels causes venting of the powder mass and reduction of the combustion gas pressure before the mass detonation rate is reached.

It is, therefore, an object of this invention to provide a system to prevent detonation of a volume of explosive material after commencement of deflagration of the explosive material.

It is a further object of this invention to provide a system of the character described which reduces pressure in the burning portion of the volume of explosive material before the mass detonation rate of the explosive is reached.

It is yet another object of this invention to provide a system of the character described which vents the burning portion of the volume of explosive material before the mass detonation rate of the explosive is reached.

These and other objects and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side sectional view of a powder hopper formed in accordance with the prior art and used for storing and dispensing of large volumes of explosive powder;

FIG. 2 is a side sectional view of a powder hopper similar to that shown in FIG. 1 but including a preferred embodiment of the invention in the form of blow-out panels on the hopper; and

FIG. 3 is an exploded view in perspective, of the paneled portion of the hopper of FIG. 2.

Referring now to FIG. 1, there is shown a sectional view of a conventional Kingsmill powder hopper used for storing and dispensing comparatively large volumes of explosive powder. The hopper 2 includes a cylindrical side wall 4 and a frustoconical bottom wall 6 opening into an exit chute 8. A cap member 10 is fitted onto the exit tube 8 and includes a valve 12 (shown schematically) through which powder 14 is fed. A plurality of supports 16 hold the hopper 2 above a surface 18 such as the ground or a floor. The top of the hopper 2 is open to the atmosphere, as at 20'. Additional powder is fed into the hopper 2 through openings 22 in the side wall 4. It has been found that if burning of the powder occurs in the area marked X generally near the apex of the bottom wall 6, detonation will be likely to occur.

Referring now to FIGS. 2 and 3, a preferred embodiment of the invention for use with a Kingsmill hopper is shown. The embodiment includes a hopper with a frustoconical bottom wall 36 having windows or cutout portions 38. At least about 30 percent of the area of the bottom wall 36 should be cut out, and preferably about percent of the area of the wall 36 is cut out. A plurality of panels 40 are tightly but lightly secured to the bottom wall 36 so as to close off the openings 38. The panels 40 are secured to the wall 36 sufficiently tightly to prevent powder from leaking through the seams, and also sufficiently tightly to prevent the panels 40 from being dislodged by the weight of the powder mass 14 in the hopper, and yet sufficiently lightly to permit the panels 40 to be dislodged by combustion gas pressure less than the gas pressure required to reach the mass detonation rate of the powder. Thus in the configuration shown in FIGS. 3 and 4, venting of the burning powder mass is caused by gas pressure from the burning powder dislodging the panels 40 before the mass detonation rate of burning is reached.

Testing of the prior art containers without and with the specific venting system was performed under the following conditions resulting in the observations set forth below. In order to determine what would happen to a conventional Kingsmill hopper in the event of an internal hopper fire, a test hopper was constructed sub stantially as appears in FIG. 1. The hopper was loaded with 150 lbs. of Class 7 smokeless powder, which is a detonatable powder used in the manufacture of shotshells and rimfire ammunition. A black powder squib was placed in the general area marked X in FIG. 1 in the powder mass, and was electrically ignited. After a time lapse of 0.030 second measured from ignition of the squib, high order detonation occurred with total destruction and complete disappearance of all pieces of the hopper. The explosion was accompanied by a violent ground and air shock wave.

Next a hopper was constructed of the same size and shape as the hopper described above, but the bottom conical wall of the hopper was modified as shown in FIGS. 2 and 3. Openings equal to about 50 percent of the total area of the bottom wall of the hopper were cut therein, and light gauge aluminum panels were installed over the openings. A resinous, resiliently setting adhesive was used to fasten the panels to the remainder of the bottom wall of the hopper so as to seal the interface of the hopper bottom wall and panels against powder leakage. The modified hopper was then loaded with 150 lbs. of Class 7 smokeless powder of the same type used in the experiment described above. A black powder squib was placed in the powder mass approximately in the area indicated by the letter X in the drawings. The squib was ignited electrically. The panels were then blown out away from the hopper by internal pressure and flames were observed to rush out through the openings which the panels had closed. No detonation occurred, and the powder charge merely burned itself up. Four additional tests were made upon similar conditions with similar results.

It will be readily appreciated that venting of the combustion gas pressure and combustion heat away from the critical area of a mass of detonatable explosive powder, and into the atmosphere, if done quickly enough, will prevent occurrence of the mass detonation rate of burning of the powder. Thus the danger of detonation of a mass of ignited powder is eliminated, and the ignited powder mass merely burns itself up. Furthermore, by properly venting the powder mass, flames of combustion can be directionalized and carried out of harm's way so as to minimize or prevent the danger of a fire accidentally started in one powder mass spreading to adjacent powder masses.

Since many changes and variations of the disclosed embodiments of the invention may be made without departing from the invention concept, it is not intended to limit the invention otherwise than as required by the appended claims.

What is claimed is:

l. A container for storing a volume of detonatable material, said container including a side wall and a frustoconical bottom wall secured to said side wall; means forming an exit chute extending from the apex of said frustoconical bottom wall; said bottom wall having open areas therein; panel means closing said open areas; and means securing said panel means to said bottom wall to seal said openings against leakage of the detonatable material, said securing means being releasable by gas pressure generated from combustion of the detonatable material in the area of said apex of said bottom wall to permit dislodgementpf said panel means from said bottom wall to cause said open areas to vent the combustion gas before the mass detonation rate of burning of the material is reached.

2. The container of claim 1, wherein said open areas are equal to at least 30 percent of the total area of said bottom wall.

3. The container of claim 1, wherein said open areas are equal to at least 50 percent of the total area of said bottom wall.

4. The container of claim 1, wherein said panels are oflight gauge aluminum.

5. The container of claim 1, wherein said securing means is a resiliently setting resinous adhesive. 

1. A container for storing a volume of detonatable material, said container including a side wall and a frustoconical bottom wall secured to said side wall; means forming an exit chute extending from the apex of said frustoconical bottom wall; said bottom wall having open areas therein; panel means closing said open areas; and means securing said panel means to said bottom wall to seal said openings against leakage of the detonatable material, said securing means being releasable by gas pressure generated from combustion of the detonatable material in the area of said apex of said bottom wall to permit dislodgement of said panel means from said bottom wall to cause said open areas to vent the combustion gas before the mass detonation rate of burning of the material is reached.
 2. The container of claim 1, wherein said open areas are equal to at least 30 percent of the total area of said bottom wall.
 3. The container of claim 1, wherein said open areas are equal to at least 50 percent of the total area of said bottom wall.
 4. The container of claim 1, wherein said panels are of light gauge aluminum.
 5. The container of claim 1, wherein said securing means is a resiliently setting resinous adhesive. 